Acoustic snowdrift measurements: experiences from the FlowCapt instrument

Three acoustic FlowCapt (TM) (IAV Engineering) drifting snow instruments were deployed during the 1999 and 2000 field season on Spitsbergen, Norway. Three different experiments were carried out to test the instruments for their use in snowdrift research. The data from the three instruments were compared during a study of drifting snow within an Arctic catchment and around a building. The principle of the instruments is based on the acoustic signal, generated by the mechanical impact of drifting snow particles on a vertical tube. Microphones inside the tube transmit the signal to a frequency analyser. By Fourier transformation, the signal can be divided into the high frequencies of the impacting snow particles and the low frequencies, resulting from the loosening wake eddies behind the tube. In this way, both snow drift flux and wind speed can be measured simultaneously. Results from the three experiments show that the instruments are useful tools to study drifting snow in remote areas. A reliable indication of the occurrence and strength of drifting snow events can be determined even if the absolute accuracy is difficult to quantify. (C) 2001 Elsevier Science B.V. All rights reserved.